Mammography's success for screening for breast cancer is mostly attributed to its capability for reliably imaging calcifications, an important marker for early stage breast cancer. Microcalcifications are present in 60-80% of breast cancers and are a reliable indicator of both benign and malignant lesions. The key diagnostic features of microcalcifications are their location, number, size, morphology, distribution, pattern, and relation to a mass. These features help stratify the risk of malignancy and often are the only marker of cancer. A relevant example is Ductal Carcinoma in Situ (DCIS), which accounts for 20% of breast cancers.
However, mammography shows poor performance in dense breast tissue, the non-fatty portion of the breast. Dense breast tissue is more commonly found in younger women, and women in certain localities, China for example.
Also, despite measures to reduce the dose, mammography exposes the patient to ionizing radiation. In addition, there is the issue of patient comfort due to the need for compression plates.
The major limitation of conventional ultrasound, which is non-ionizing and needs no compression plates, is its poor sensitivity to microcalcifications. The sensitivity to microcalcifications is within 50-80%.
Mallart discloses phase aberration correction of an ultrasonic transmit beam for the inhomogeneities of a medium through the use of a receive focusing criterion that is independent of both the scattering cross-section of the medium and the transmitted energy. See R. Mallart and M. Fink, “Adaptive focusing in scattering media through sound-speed inhomogeneities: The van Cittert Zernike approach and focusing criterion,” J. Acoust. Soc. Am., vol. 96, no. 6, pp. 3721-3732, 1994.